Cliff worked in Swansea docks during World War II and turned to boxing as a profession towards the end of the conflict, in 1944.
He soon built an impressive winning record, including a memorable victory over fellow Swansea fighter Ronnie James at the Vetch Field in 1947.
James – who is reported to have been unwell in the build-up – was on the canvas in the third, and his corner threw in the towel in the seventh round.
Major titles proved elusive for Curvis, though. A 1946 British featherweight eliminator against Al ‘the Aldgate Tiger’ Phillips was one of just two defeats on Curvis’s record in a busy first four years as a professional.
The losses began to mount after a 1948 defeat to Peter Fallon, but the biggest fights were still to come for Curvis.
A 1950 revenge win over fellow Welshman Gwyn Williams was a British welterweight title eliminator.
When his shot at the belt came it was against another Welsh great – champion Eddie Thomas.
In a huge showdown at Swansea’s St Helen’s – the first British title fight held between two Welshmen in Wales – Thomas had his jaw dislocated in the fourth round.
But it was re-set, and the Merthyr iron man went on to a deserved points victory, a decision that infuriated the local crowd.
A year later, Curvis lost another British title eliminator, this time against Wally Thom.
But after Thom went on to dethrone Thomas, the new champion gave Curvis the first shot at his British and Commonwealth belts.
The 24 July, 1952, would finally be the Swansea man’s time to claim title glory as he dethroned Thom with a ninth-round knock-out in Liverpool.
After a non-title win over Danny Womber, the new champion would lose his Commonwealth belt in his first defence, against Gerald Dreyer.
The bout was in the South African’s home town of Johannesburg, and Curvis is reported to have become the first British fighter to fly abroad for a contest.
He had the challenger down in the sixth – Dreyer’s recovery allegedly helped by a long count – but broke his hand in the same round.
The contest went the full 15, but the handicapped Welshman lost the verdict.
Curvis would fight just once more, a 1952 bout against Gilbert Lavoine for the vacant European welterweight crown.
The then-25-year-old Welshman travelled to Paris, but saw his hopes ended when he was disqualified in the 10th.
He was not finished with boxing, though, and when his outstanding brother Brian turned professional in 1959 Cliff was his manager and trainer.
Although the partnership proved very successful in the ring, it would later turn horribly sour with lasting disputes over money that forever poisoned fraternal relations.
“There wasn’t very good management [off Cliff],” said Brian Curvis in a 1989 BBC documentary. “I’m rather surprised looking back over my career and so many big-money championship fights that there were no real accounts kept and I did not have a great deal of money.”
Cliff also served for many years with the British Boxing Board of Control, ran his own building company, and was landlord of the Villiers pub in Swansea’s Hafod district.
He died in 2009, at the age of 81.